The recent expansion of the invasive hemiparasitic plant Cassytha filiformis and the reciprocal effect with its main hosts

Abstract Cassytha filiformis is a hemiparasitic plant that causes severe effects in its host plants. Since this decade, this alien species has been increasing its distribution towards the coastal areas of the Peninsula of Yucatán, parasitizing shrub species that play a crucial role in the containment of soil erosion. Here we studied the current distribution of C. filiformis along the coastal dune in northern Yucatán, recording the frequency of parasitism and the identity of its host plants. In addition, we evaluated the effect of C. filiformis on the sexual reproductive success of the main host plants and the effect of host species identity on C. filiformi’s reproductive success. We found that the distribution of C. filiformis occurs throughout the coastal dunes of Yucatan (covering ≈250km), parasitizing 15 species. However, ca. 70% of C. filiformis plants occur on three common shrub species: Suriana maritima, Scaevola plumieri, and Tournefortia gnaphalodes. The frequency of parasitized plants by C. filiformis was not dependent on host plant abundance. T. gnaphalodes suffer a higher proportion of parasitism. The reproductive success of the three host plants was lower in the presence of the parasitic plant. On the other hand, C. filiformis showed higher reproductive success when parasitizing S. maritima. Our results suggest that C. filiformis has extensively invaded the Yucatán coastal dunes, significantly reducing the sexual reproduction of its host-plant species. Overall, our results suggest that C. filiformis has the potential to cause significant damage in the Yucatán coastal dune community.